Pelion Device Management Client example for Mbed OS

This is a basic Device Management Client example for Mbed OS that supports:

• The latest Mbed OS and Device Management Client releases.
• Developer mode provisioning.
• Firmware Update.

There is a more advanced example of the client with support for multiple operating systems in mbed-cloud-client-example repository. The underlying client library is the same for both. This Mbed OS only example is simpler as it only supports one OS with a limited set of demonstrated features. If you want to do development in Linux and Mbed OS at the same time - you should use the mbed-cloud-client-example.

Note: If you want to use production provisioning modes, or use more advanced client features, those are demonstrated via mbed-cloud-client-example.

Supported boards

This table shows a list of boards that are supported.

Build-only = This target is currently verified only via compilation, and is not verified at runtime.

Developer guide

This section is intended for developers to get started, import the example application, compile and get it running on their device.

Requirements

• Mbed CLI >= 1.10.0

  For instructions on installing and using Mbed CLI, please see our documentation.

• Generate your own access key. Pelion Device Management is available for any Mbed developer. Create a free trial.

  For instructions on how to generate your access key, please see our documentation.

Deploying

This repository is in the process of being updated and depends on few enhancements being deployed in mbed-cloud-client. In the meantime, follow these steps to import and apply the patches before compiling.

```
mbed import mbed-os-example-pelion
cd mbed-os-example-pelion
```

Preparing for build

1. Configure Mbed CLI defaults:

   mbed target K64F
   mbed toolchain GCC_ARM

2. Download the developer certificates from the Device Management Portal:

   1. Log in to the portal with your credentials.
   2. Navigate to Device identity > Certificates.
   3. Click New certificate.
   4. Add a name and an optional description for the certificate, and click Create certificate.
   5. Go to Device identity > Certificates again.
   6. Click on your new certificate.
   7. Click Download developer C file to download the file mbed_cloud_dev_credentials.c.

3. Copy the mbed_cloud_dev_credentials.c file to the root folder of the example.

4. Use manifest-tool python package to create an update-related configuration for your device:

   1. Install the requirements.txt from the application to get the supported version of manifest-tool:

      pip install -r requirements.txt

   2. Initialize the developer environment:

      manifest-dev-tool init --access-key <Device Management access key>

Compiling

mbed compile

Program Flow

1. Initialize, connect and register to Pelion DM
2. Interact with the user through the serial port (115200 bauds)
   • Press enter through putty/minicom to simulate button
   • Press i to print endpoint name
   • Press Ctrl-C to to unregister
   • Press r to reset storage and reboot (warning: it generates a new device ID!)

Further information and requirements

Check the public tutorial for further information:

https://www.pelion.com/docs/device-management/current/connecting/mbed-os.html

Enabling logs

Logging (or tracing) can be enabled by modifying the mbed_app.json file.

```
        "mbed-trace.enable"                         : null,
```

By modifying that null to 1 and recompiling the application.

Log level can be modified compile-time by defining MBED_TRACE_MAX_LEVEL -macro to mbed_app.json:

    "target.macros_add": [
         "MBED_TRACE_MAX_LEVEL=TRACE_LEVEL_INFO",

Default level is TRACE_LEVEL_DEBUG, possible values are:

• TRACE_LEVEL_DEBUG (largest amounts of logs)
• TRACE_LEVEL_INFO
• TRACE_LEVEL_WARN and
• TRACE_LEVEL_ERROR (smallest amount of logs).

Component level run-time control is also possible by setting log levels (by calling mbed_trace_config_set()) and inclusions/exclusions (by calling mbed_trace_include_filters_set() or mbed_trace_exclude_filters_set()`).

For more details, see the mbed-trace library.

Troubleshooting

• Device initializes but can't register to Pelion

  Error: client_error(3) -> Bootstrap server URL is not correctly formed

  Solution: Format the the storage by pressing 'r' in the serial terminal.

Porting process to add support for an Mbed Enabled board

There are many steps involved in this process. We generally recomend the following steps:

1. Configure the application using mbed_app.json
   • Configure the default connectivity
   • Configure the KVSTORE area to store credentials (internal or external memory)
   • Build the application, program the board and observe whether the application can connect to Pelion DM by using a serial terminal.
2. Configure the bootloader using bootloader_app.json
   • Configure the KVSTORE area
   • Configure the FW Candidate Storage
   • Build bootloader application, program the board and observe whether this is able to boot.
3. Enable application with bootloader using mbed_app.json
   • Enable the usage of the bootloader
   • Ensure the KVSTORE addresses and FW Candidate storage addresses match with the bootloader configuration
   • Build the application again (this time combined with bootloader) and check whether it can boot and connect to Pelion DM.
   • Perform a FW Update and check whether the process can be completed succesfully.

1. Application configuration

Note: consider allocating the credentials on internal flash to simplify the application setup process. In addition, consider the use of internal flash to store the firmware candidate image for the FW update process as this would remove the need to use external components. If there isn't enough space, you may need to enable external storage (SD Card, SPI, etc).

Mbed OS boards should have a default configuration for connectivity and storage in Mbed OS (targets.json). You can extend or override the default configuration using mbed_app.json in this application. Create a new entry under the target name for your device.

a. Connectivity

Specify the default IP connectivity type for your target. It's essential with targets that lack default connectivity set in targets.json or for targets that support multiple connectivity options. For example:

  "target.network-default-interface-type" : "ETHERNET",

The possible options are ETHERNET, WIFI and CELLULAR.

Depending on connectivity type, you might have to specify more configuration options. Review the documentation for further information.

b. Storage for credentials

Start by getting familiar with the multiple storage options and configurations supported in Mbed OS.

Then start designing the system memory map, the location of components (whether they are on internal or external memory), and the corresponding base addresses and sizes. You may want to create a diagram similar to the one below to help you to make design decisions:

+--------------------------+
|                          |
|                          |
|                          |
|Firmware Candidate Storage|
|                          |
|                          |
|                          |
+--------------------------+ <-+ update-client.storage-address
|                          |
|         KVSTORE          |
|                          |
+--------------------------+ <-+ storage_tdb_internal.internal_base_address
|                          |
|        Free space        |
|                          |
+--------------------------+
|                          |
|                          |
|        Active App        |
|                          |
|                          |
|                          |
+--------------------------+ <-+ mbed-bootloader.application-start-address
|Active App Metadata Header|
+--------------------------+ <-+ update-client.application-details
|                          |
|        Bootloader        |
|                          |
+--------------------------+ <-+ 0

In cases where the MCU has two separate memory banks, it's appropiate to allocate the bootloader and base application in one bank, and KVSTORE storage at the begining of the second bank followed by a firmware candidate storage.

• Option 1: Allocating credentials in internal memory

  This is the preferred option whenever possible. Make sure TDB_INTERNAL is the type of storage selected in mbed_app.json. Specify the base address depending on the available memory in the system. The size of this section should be aligned with the flash erase sector. The value should be multiple of 4 with a minimum of 24KB and upwards depending on the use case (for example the usage of certificate chain will increase the need of storage to hold those certificates). An example of this configuration can be seen for the NUCLEO_F429ZI board in this application.

  "storage.storage_type"                      : "TDB_INTERNAL"
  "storage_tdb_internal.internal_base_address": "(MBED_ROM_START+1024*1024)",
  "storage_tdb_internal.internal_size"        : "(128*1024)",

• Option 2: Allocating credentials in external memory:

  This is possible when the board has an storage device wired to the MCU (could be on-board or external component). Make sure FILESYSTEM is specified as type of storage. The blockdevice and filesystem should be one of the supported in Mbed OS (see docs).

  An example of this configuration can be seen for the K64F board in the mbed-cloud-client-example

  "storage.storage_type"                      : "FILESYSTEM",
  "storage_filesystem.blockdevice"            : "SD",
  "storage_filesystem.filesystem"             : "LITTLE",
  "storage_filesystem.internal_base_address"  : "(32*1024)",
  "storage_filesystem.rbp_internal_size"      : "(8*1024)",
  "storage_filesystem.external_base_address"  : "(0x0)",
  "storage_filesystem.external_size"          : "(1024*1024*64)",

c. Storage for firmware updates

Before enabling FW updates, it's recomended that the application is able to initialize the network and connect to Pelion DM.

Once the connection is successfull, you can follow the steps below to enable the board to receive FW updates. Note the configuration for the application in this section should match with the one on the bootloader - see section below.

• Common configuration

  Regardless of where the firmware candidate is located (internal or external), there is a need to have a bootloader in place. The binary of the booloader can be specified with the bootloader_img option. The address and size of the bootloader determines the application-details and bootloader-details options. The value of bootloader-details can be obtained by checking for the symbol from the map file of the binary. Example python code for obtaining the location:

  with open("BUILD/UBLOX_EVK_ODIN_W2/GCC_ARM/mbed-bootloader.map", 'r') as fd:
      s = fd.read()
  
  regex = r"\.rodata\..*{}\s+(0x[0-9a-fA-F]+)".format("bootloader")
  match = re.search(regex, s, re.MULTILINE)
  offset = int(match.groups()[0], 16)
  print hex(offset)

  Review the mbed-bootloader guidelines on how these options should be selected. Review the bootloader configuration section below for more information.

  Copy the compiled bootloader from mbed-bootloader/BUILDS/<TARGET>/<TOOLCHAIN>-TINY/mbed-bootloader.bin to bootloader/mbed-bootloader-<TARGET>.bin.

  Edit mbed-os-pelion-example/mbed_app.json and modify the target configuration to match with the one in bootloader_app.json.

  Note:

• update-client.application-details should be identical in both bootloader_app.json and mbed_app.json.

• target.app_offset is relative offset to flash-start-address you specified in mbed_app.json and bootloader_app.json, and is the hex value of the offset specified by application-start-address in bootloader_app.json. For example, (MBED_CONF_APP_FLASH_START_ADDRESS+65*1024) dec equals 0x10400 hex.

• target.header_offset is also relative offset to the flash-start-address you specified in the bootloader_app.json, and is the hex value of the offset specified by update-client.application-details. For example, (MBED_CONF_APP_FLASH_START_ADDRESS+64*1024) dec equals 0x10000 hex.

  An example of this configuration can be seen for the NUCLEO_F429ZI board.

  "update-client.application-details"         : "(MBED_ROM_START + MBED_BOOTLOADER_SIZE)",
  "update-client.bootloader-details"          : "0x08007300",
  "target.bootloader_img"                     : "bootloader/mbed-bootloader-<target>",
  "target.header_offset"                      : "0x8000",
  "target.app_offset"                         : "0x8400",

• Option 1: Allocating the firmware update candidate in internal memory

  This is the preferred option whenever possible. Make sure ARM_UCP_FLASHIAP is selected in update-storage in mbed_app.json. This area should be located at the end of the flash after the KVSTORE area. Specify the storage-address, storage-size and storage-page as required. The application-details option should point at the end of the bootloader area. An example of this configuration can be seen for the NUCLEO_F429ZI board.

  "mbed-cloud-client.update-storage"          : "ARM_UCP_FLASHIAP",
  "update-client.storage-address"             : "(MBED_CONF_STORAGE_TDB_INTERNAL_INTERNAL_BASE_ADDRESS+MBED_CONF_STORAGE_TDB_INTERNAL_INTERNAL_SIZE)",
  "update-client.storage-size"                : "(1024*1024-MBED_CONF_STORAGE_TDB_INTERNAL_INTERNAL_SIZE)",
  "update-client.storage-page"                : 1,

• Option 2: Allocating the firmware update candidate in external memory

  When using an external device to the MCU to store the firmware candidate, make sure ARM_UCP_FLASHIAP_BLOCKDEVICE is specified as type of update-storage. Specify the storage-address, storage-size and storage-page as required.

  An example of this configuration can be seen for the K64F board in the mbed-cloud-client-example

  "mbed-cloud-client.update-storage"          : "ARM_UCP_FLASHIAP_BLOCKDEVICE",
  "update-client.storage-address"             : "(1024*1024*64)",
  "update-client.storage-size"                : "((MBED_ROM_START + MBED_ROM_SIZE - APPLICATION_ADDR) * MBED_CONF_UPDATE_CLIENT_STORAGE_LOCATIONS)",

2. Bootloader configuration

The bootloader is required to perform FW Updates. The steps below explain how to create a new configuration and binary for the bootloader.

1. Import as a new application the mbed-bootloader repository.

2. Edit the bootloader application configuration in this example (bootloader/bootloader_app.json) and add a new target entry. An example of this configuration can be seen for the NUCLEO_F429ZI board:

   "update-client.firmware-header-version" : "2", "mbed-bootloader.use-kvstore-rot" : 0, "mbed-bootloader.bootloader-size" : "APPLICATION_SIZE", "update-client.application-details" : "(MBED_ROM_START + MBED_BOOTLOADER_SIZE)", "mbed-bootloader.application-start-address": "(MBED_CONF_UPDATE_CLIENT_APPLICATION_DETAILS + MBED_BOOTLOADER_ACTIVE_HEADER_REGION_SIZE)", "mbed-bootloader.max-application-size" : "(MBED_ROM_START + MBED_BOOTLOADER_FLASH_BANK_SIZE - MBED_CONF_MBED_BOOTLOADER_APPLICATION_START_ADDRESS)", "update-client.storage-address" : "(MBED_ROM_START + MBED_BOOTLOADER_FLASH_BANK_SIZE + KVSTORE_SIZE)", "update-client.storage-size" : "(MBED_BOOTLOADER_FLASH_BANK_SIZE - KVSTORE_SIZE)", "update-client.storage-locations" : 1, "kvstore-size" : "2641024", "update-client.storage-page" : 1

3. Compile the bootloader using the bootloader_app.json configuration you've just edited:

   mbed compile -t <TOOLCHAIN> -m <TARGET> --profile=tiny.json --app-config=.../mbed-os-pelion-example/bootloader/bootloader_app.json>

Note: mbed-bootloader is primarily optimized for GCC_ARM, so you may want to compile it with that toolchain. Before jumping to the next step, you should compile and flash the bootloader and then connect over the virtual serial port to ensure the bootloader is running correctly. You can ignore errors related to checksum verification or failure to jump to application - these are expected at this stage.

Validation and testing for the board configuration

The board needs to pass the underlying Mbed OS tests and be supported by official Mbed OS release.

• Mbed OS tests (as described in our documentation)

  cd mbed-os
  mbed test -m <target> -t <toolchain>

• Mbed OS integration tests

  See mbed-os/TESTS/integration/README.md (sip-workshop branch)

  cd mbed-os
  mbed test -t <toolchain> -m <board> -n *integration-* -DINTEGRATION_TESTS -v

Validation and testing for the client configuration

Basic pelion features are required to work:

• Connects to Pelion in developer mode.
• Firmware can be updated.
• Responsive to REST API commands.

This should be verified by executing the Pelion E2E python test library tests.

• Install the prerequisites listed in the README of the pelion-e2e-python-test-library.
• Configure your access key as instructed in the same README.

• Basic tests can be then executed as:

  pytest TESTS/pelion-e2e-python-test-library/tests/dev-client-tests.py --update_bin=/home/user/mbed-os-example-pelion/mbed-os-example-pelion_update.bin

Contributing platform support

The contribution of platform support to this repository is restricted to Arm Mbed Partners and Arm Engineering teams. If you’d like to add a custom or community-based platform, please fork this repository and add it into your own account. Expectations on contributions:

• No code changes in main.cpp. This is a minimal and generic application that’s expected to work on out of the box with all platforms listed in the documentation and Pelion Quick-start guide.

• No changes to the hash of mbed-os.lib or mbed-cloud-client.lib files. The Mbed OS release used in this repository should be update-to-date but you can raise an issue to be updated by the maintainers.

• No extra files or .mbedignore with removal of Mbed OS code. You may need to fix issues and send a PR to Mbed OS first.

• Configuration (required)

  • mbed_app.json to add components or features. Please follow the guidelines in the porting section of the docs.

• Drivers (optional)

  • If required, drivers for networking or storage (non-default) can be added in the drivers folder using an external library (.lib). For example COMPONENT_MYDRIVER.lib and enabling in mbed_app.json.

• Bootloader (required)

  • The configuration should be provided in either mbed-bootloader repository (as default configuration) or bootloader folder in this repository (if non-default). Our recommendation is to contribute to the mbed-bootloader repository whenever possible. Please indicate where the bootloader configuration lives.
  • Binaries should be generated and contributed following the name conventions in the bootloader folder.

• Indication of platform support

  • Please update README.md file and add an entry to the list of supported boards.

• Test results and other information

  • Attach test logs for required toolchains as documented here
    • Greentea (Mbed OS tests, including integration tests).
    • Pelion E2E tests based on pytest.
  • Mbed OS and Mbed-cloud-client version used during the tests. Note contributions will be accepted only against versions available in the example at that time.

• Pull-requests are raised against the master branch. The Arm team makes releases regularly.

• Pelion-Ready. Indicate if a board is expected to be marked as Pelion-Ready and therefore be added to the Pelion Quick-start.

• You agree that the configuration changes contributed are considered open source and Apache 2.0 licensed.

• Support of the platform is provided by Silicon Partners or Platform vendors for Mbed Enabled platforms. If using a non-default configuration, then Arm is responsible for its support.

Note platforms will be tested regularly in the Arm CI system. Please discuss with your Arm contact and make hardware available as indicated in the Mbed Enabled requirements.

Known-issues

Please review existing issues on GitHub and report any problem you may see.